JPS61185376A - Method of reducing nickel content in waste water - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a method for reducing soluble and insoluble nickel impurities in wastewater. In general detail, the present invention provides a method for reducing the total nickel content of gray water and effluent from a partial oxidation process to obtain an effluent stream that is acceptable to the environment or to a circulating water system. The present invention relates to a method for preventing nickel from being accumulated and nickel carbonyl from being completely produced.

[Background] Nickel from soluble and insoluble nickel compounds can be present in dilute to dilute wastewater from chemical processes such as partial oxidation processes in concentrations of about 1 to 15 mg per part. Recirculating such water into the process can significantly increase the nickel concentration within the system. Depending on environmental regulations, the total concentration of nickel from each water-soluble and water-insoluble nickel compound must be reduced to 1 before discharging such water to the sewer.
It is advisable to reduce the dose below.

By partial oxidation of a liquid hydrocarbon fuel, such as a liquid hydrocarbon fuel, an oxygen-containing hydrocarbon fuel, or a slurry of a solid hydrocarbon fuel supported by water and/or liquid hydrocarbons, synthesis gas, reducing gas or fuel can be produced. In the process of producing gas, gray water from a decanter is
) and gas quenching and/or cleaning operations to reduce the total nickel content in the effluent to levels that are acceptable to the environment prior to discharge from the system. In order to avoid the formation of volatile nickel carbonyls, it is desirable to prevent nickel from accumulating in the quenching and/or cleaning water circulation system during the partial oxidation process. Nickel carbonyl tends to decompose and form undesirable nickel deposits on the walls of heat exchangers. For example, if traces of H and S remain in the gas, nickel sulfide can accumulate on the walls of the heat exchanger, causing negative metallurgical effects. Additionally, in low temperature catalytic synthesis, nickel carbonyl can be decomposed in a mixture of hydrogen and carbon monoxide. Nickel can then accumulate in both homogeneous and heterogeneous noble metal catalyst systems, adversely affecting catalyst selectivity and activity.

Applicant's U.S. Pat. No. 4.4, incorporated herein by reference.
No. 211.646 relates to a method for removing cyanide, sulfide, ammonia, soot, and insoluble metals in scrubbing water from a partial oxidation process. Clarification, filtration and steam stripping after addition of ferrous sulfate and lime are employed.

However, it has been found that that method cannot consistently reduce soluble nickel to extremely low limits.

Surprisingly, the method of the present invention allows gray water from the decanter in the carbon recovery system of the partial oxidation step and effluent from gas quenching and/or cleaning operations to be
The concentration of nickel in wastewater (such as own water) must be kept at a level that is acceptable to the environment, e.g. 0.5 m g/
It was found that the decrease was consistent down to levels below 1 mg/l, such as 1 mg/l. Moreover, these levels could not be consistently achieved simply by adding dimethyl glyochime to gray water.

[Association]

The present invention provides a method for reducing soluble and insoluble nickel impurities in wastewater, such as gray water and gases from decanting operations of partial oxidation processes, effluents from quenching and/or washing operations.

In the present invention, nickel impurities are present in wastewater containing (1) water-soluble compounds selected from formaldehyde, ionizable polysulfides (e.g., alkali metal or ammonia polysulfides), and hydrogen peroxide; ) Dimethyl glyochime is added and, if necessary, a base is added to bring the pH to a range of 7-11.

In a preferred embodiment of the process of the invention, 1 ton of wastewater at a temperature of 15 to 105° C. contains 10 to 1000 mg of water-soluble substances (
11 and 2 to 10 moles of dimethyl glyochime (2) per atom of dissolved nickel. The pH of this diluted mixture is adjusted to the desired value in the range from 7 to 11 by addition of a base, such as NaOH or Ca(OH)2, if the pH is not already at said desired value.

A precipitate consisting of a nickel-dimethylglyoxime complex is formed which is separated by at least one conventional solid-liquid separator from at least a portion of the insoluble nickel and its compounds, other insoluble impurities such as particulate carbon, soot, or separated from the water together with at least a portion of the metals v and Fe or their sulfides. Suitable solid-liquid separators can be selected from the group consisting of filters, centrifuges, liquid buclones, settling tanks, clarifiers, and combinations thereof. In this way, the nickel content of the wastewater is reduced to an environmentally acceptable emission level and nickel is prevented from accumulating in the recirculating water system.

〔Example〕

In one embodiment, the wastewater contains, in addition to soluble nickel impurities, at least one of the following soluble and/or insoluble impurities: i.e. nickel and nickel compounds,
Contains at least one of formates, fanides, ammonia, halides of metals or ammonia, metals and sulfides of gold and/or Fe, particulate carbon and soot.

Waste water, eg gray water, may or may not be degassed prior to treatment. Water-soluble and water-insoluble impurities can be reduced by the following steps. That is, 15 to 10
Gray water at a temperature in the range of 5° C. is treated with dimethyl glyochime and a water-soluble substance selected from the group consisting of HCHO, ionizable polysulfides such as alkali metal polysulfides or ammonium polysulfides, and H2O2. , a ferrous compound, such as ferrous sulfate or ferrous chloride, and a basic substance, such as NaOH or Ca(OH)z, which adjusts the pH of the gray water mixture to the desired value in the range from 7 to 11. mixing with;
Precipitating CN-containing sludge, such as iron cyanide, iron hydroxide and iron sulfide;
iron hydroxide and other water-insoluble substances such as particulate carbon, soot, nickel and its compounds, such as nickel sulfide and at least a portion of the metals and sulfides of metal V and/or Fe, in at least one conventional It can be reduced by separating in a liquid separator to obtain a clear water stream with a total nickel content of less than 1 mg/Z.

At least a portion of this clear water stream can be recycled to the quenching and/or washing zone. According to another embodiment, ammonia or ammonia and, if present in the clear water stream, sacrificial salts can be removed by the following steps. In other words, a: If the pH of clear water is 11 or less, increase the pH to at least 11; strip NI (8) from clear water; NH3
The clarified water stripped of NH8 is introduced into a conventional bioreactor after its pH is adjusted to a value in the range of about 6 to 8; and the formate and excess Organic substances such as dimethyl glyochime can be removed from clear water in a bioreactor to provide CO2, biological residue suitable for disposal, and a remedial water stream. At least a portion of the improved water flow includes gas quenching and/or
Or it can be recycled to the wash zone and the remainder can be discharged from the system. By means of the method of the present invention, the nickel content of the remediation water stream can be consistently reduced to levels that are acceptable to the environment. Additionally, the levels of nickel and ash in the recirculating water system can be controlled.

Nickel is present and trapped as an impurity in liquid hydrocarbonaceous fuels and solid carbonaceous fuels along with sulfur-containing and nitrogen-containing compounds. For example, nickel may be present in fuels and coal in a range of about 3 to 70 ppm. Applicant's U.S. Pat. No. 3,544,29, incorporated herein by reference.
No. 1, No. 3,998,609, No. 4.014,786
No. 4,141,696 and No. 4,110,359
For the production of gaseous mixtures consisting of H2 and CO, such as those described in No. It is reacted with a free oxygen-containing gas, such as substantially pure oxygen, and optionally a supplemental temperature control agent. Nickel contaminants in the feedstock are converted to precipitated nickel metal, nickel sulfide, and surprisingly high levels of soluble nickel during the gasification process. Particulate carbon is also produced in the reaction zone of the partial oxidation gas generator, and metallic Ni
, V and Fe metals and some of the sulfides, such as ash, may be retained to form soot. These nickel products leave the reaction zone entrained in the hot crude gas stream and can then be transferred to the quench and wash water.

HCN and H2S are trace impurities in the crude gas stream from the partial oxidation gas generator and form compounds with nickel. For example, water-soluble N1 (CN) = and N, which is water-soluble in the alpha or beta type and water-insoluble in the gamma type.
iS also exists. The hot crude gas stream from the partially oxidized gas generator, containing accompanying materials such as particulate carbon, ash, soot and slag, is cooled in quench water at a temperature in the range of 150-320°C and then immersed in water. is used to remove accompanying particulate matter. The hot crude gas stream undergoes indirect heat exchange with water in a gas cooler and is then cooled to a temperature in the range of 175-375°C in direct contact with water in a flapper. In an example such as that described in U.S. Pat. No. 4,110,359 to Kazuto Motoyama, a hot crude gas stream is divided into two gas streams. Each gas flow is then 24" as described above.
It is cooled and washed with water using a +4 hard cooling method. Substantially all entrained material is transferred to the quench and/or wash water to provide a purified stream of syngas, reducing gas, or fuel gas.

To prevent impurities from accumulating in the quenching and cleaning water,
It is necessary to periodically discharge some of the water for quenching and washing into the sewer and compensate for this with fresh water.

The important point is that the soluble and insoluble Nt content in the effluent stream complies with environmental regulations.

When soluble and insoluble nickel compounds become highly soluble in the quenching and/or washing water and are brought into contact with high-pressure carbon monoxide, nickel carbonyl vapor is formed in the quench tank, and the amount produced is increased in the carbon scrubber. The lower the temperature, the more it increases. The small amounts of nickel carbonyl formed, e.g. about 10-10 to 10-8 moles of nickel carbonyl per mole of free gas, can cause technical problems in the subsequent handling and utilization of the gas. For example, if the gas flow is
When heated above 20°C, nickel carbonyl
! You can There, nickel deposits accumulate on the walls of the heat exchanger and have deleterious metallurgical effects. Therefore, if trace amounts of sulfide remain in the gas, the nickel sulfide produced can soak austenitic steel.

Similarly, any nickel carbonyl in a mixture of hydrogen and carbon monoxide, such as those used in low temperature chemical synthesis, can be decomposed. There, nickel accumulates in the catalyst system and adversely affects the selectivity and activity of related homogeneous or heterogeneous noble metal catalyst systems.

By the method of the present invention: 1. Soluble and insoluble nickel compounds in the quench and wash water are reduced to acceptable levels so that the aforementioned problems are avoided.

The term "gray water" used herein as a type of wastewater
is the diluted wastewater that is separated from the dispersion of carbon-liquid organic extractant in a decanter.

The decanting operation is part of the carbon recovery operation in the partial oxidation step, whereby at least a portion of the dilute carbon dispersion in the quench and wash water is regenerated by removing the majority of particulate carbon, soot and ash. be done. At least a portion of the gray water from the decanter is treated to improve water according to the method of the present invention. The wastewater stream from the quench zone of a partially oxidized system is described in detail in my US Pat. No. 4,211,646, which is incorporated herein by reference.

In a decanting operation, a stream of quenching and/or washing water containing dispersed materials, such as particulate carbon, soot and ash, is mixed with a liquid organic extractant and introduced into a one- or two-stage decanter, where the gray water is Separate and settle to the bottom. Gray water consists of water containing 100-500 ppm (by weight) of particulate carbon and about 20-85 wt.% water-insoluble ash. The ash consists of metal sulfides and metals selected from the group consisting of nickel, vanadium, iron and mixtures thereof. Gray water also contains H2S, Co2. N
It may also contain gaseous impurities selected from the group consisting of H8 and mixtures thereof. A dispersion of particulate carbon, soot, liquid organic extractant and remaining insoluble ash floats above the gray water layer. The two streams are taken separately from the decanter. at least a portion of the gray water stream;
For example, 5 to 100 volumes of water, degassed or undegassed, are treated by the method of the invention to provide improved water, and then at least a portion of the improved gray water, e.g.
~100 volumes are recycled to the quench and wash zone. The remainder of the improved gray water flow can be drained from the system. The decanting operation is described in more detail in Applicant's US Pat. No. 4,014,786, which is incorporated herein by reference. The term "degassing" refers to H2S, C
O8lCo2. Refers to the removal of gaseous impurities selected from the group consisting of NH8 and mixtures thereof. Degassing of gray water in flash towers is fully described in my US Pat. No. 4,141,696, which is incorporated herein by reference.

Environmentally acceptable wastewater effluent streams from the quench tank and/or the scraping operation can be periodically drained from the system. The nickel content of the improved gray water and discharged wastewater was reduced by the method of the present invention to a level that meets environmental regulations.

The method of the present invention relates to a method for reducing soluble and insoluble nickel-containing impurities, together with other water-insoluble substances, in a dilute waste water stream, such as gray water from a decanter or effluent, and the method comprises the steps of: . (1) Contains less than 4 parts by weight of total solids (dissolved and suspended), including nickel impurities and optionally carbon-soot and ash, degassed or non-degassed, 15 to 10
When a dilute wastewater stream at a temperature in the range of 5°C, e.g. 90-105°C, is mixed with (a), (b): (a) formaldehyde; Ammonium sulfide, e.g. NaSx
, KSx, LiSx.

NH4Sx, and mixtures thereof (where x=
(2 to 8); and hydrogen peroxide; and (b) dimethyl glyoxime; (3) precipitating the water-insoluble nickel-dimethyl glyoxime complex from the waste water stream from +21; and (4) In at least one conventional solid-liquid separation means, the two-inchelodimethel glyoxime complex in the water stream from (3) is removed from other water-insoluble substances, such as nickel and its compounds, particulate carbon, soot, metal V and/or Separated with Fe gold beak and sulfide, total nickel content is 1 m
Obtaining improved water flow reduced to less than g/A.

In step f1) of the process, a sufficient amount of the substances listed in (&) is mixed with the wastewater to convert substantially all of the soluble nickel compounds in the wastewater into a form that can be precipitated by dimethyl glyoxime. For example, because of this, wastewater 1
Approximately 10-1000 mg of the substance selected in (a) per
, for example, in the range of 20 to 500 mg.

The amount of dimethyl glyol-P7 added in (b) is
About 2 to 10 moles per atom of dissolved nickel, such as about 3 to 10 moles per atom of dissolved nickel.
Consists of 5 moles of dimethyl glyoxime. These substances can be mixed with the wastewater separately in the order described above, ie first (a) and then (b). In one embodiment,
About 1-10 ppm (by weight) of flocculants/coagulants, such as cationic electrolytes, can also be mixed with the wastewater.

Conventional solid-liquid separation means in step (4) are selected from the group consisting of filters, centrifuges, hydrocyclones, clarifiers, settling tanks and combinations thereof. In one embodiment, the solid-liquid separation means consists of a plurality of conventional liquid buikrons connected in parallel and/or in series.

In another embodiment, the wastewater is gray water, degassed or not, from the decanting operation of the partial oxidation process. Soluble and insoluble nickel and nickel compounds from gray water, as well as other soluble and insoluble impurities that may be present, such as gold (4V and/or Fe metals and sulfides,
Removed along with particulate carbon, soot, cyanide, formate and ammonia. Halides may also be present.

This example consists of the following steps. That is, (1) mixing gray water, degassed or not, from a decanting operation of a partially oxidized gas generating system and at a temperature in the range of 15 to 105° C. with (a) to (c): (a)H
a substance selected from the group consisting of CHO, ionizable polysulfides such as alkali metal polysulfides or ammonium polysulfides; (b) dimethyl glio-P7; (C) ferrous compounds; and (d) the pH of the gray water mixture.
basic substances such as NaOH or Ca(OH)21(2) water-insoluble nickel-dimethyl gliothium complex, inorganic CN-containing sludges such as iron cyanide, water precipitating iron oxides and iron sulfides; and (3) from the water stream in at least one conventional solid-liquid separation means, from the metals and sulfides of nickel and its compounds, particulate carbon, soot and gold gv and/or Fe. at least a portion of the water-insoluble substance consisting of (2)
) to obtain a clear water stream with a total nickel content of less than 1 mg/L. At least a portion of the clear water stream may be recycled to the quenching and/or washing zone. In another embodiment, ammonia is removed from clear water by the following steps. (4) raising the pH of the clear water to a minimum of 11 when it is not already at the lowest IIK; and 15
) removed by stripping the ammonia from the clear water stream from (4) using, for example, steam. N
At least a portion of the H8-stripped water, for example 5 to 100 volume t%, can be discharged from the system. Alternatively, the formate and organic materials in the NH8 stripped water can be removed prior to discharge.

In this case, the following process is added. That is, (6)N
The clear water from (5) stripped of H8, after adjusting its pH to a value in the range of about 6-8, is introduced into a conventional bioreactor where the organic matter is consumed or the carbon dioxide and separation of the fertile water stream into biological residues suitable for disposal. A portion of the clear water from (5) stripped of NHB or a portion of the improved water stream from 1 sword is
It can advantageously be recycled to gas quenching and/or cleaning operations in the partial oxidation step. The remainder can be safely drained from the system.

The concentrations of the substances in step (1) (a) and (b) are the same as those specified above in connection with the previous examples. (1)(e
The ferrous compound of ) can be a ferrous salt, such as ferrous sulfate or ferrous chloride, and may be a ferrous compound (1) containing all the ferrous ions (free) remaining in the wastewater after reaction of the substances of (a). and combination)
The amount can be 5 moles of the number of moles of .

The amount of ferrous ion introduced is sufficient to react with the remaining uncomplexed free iron cyanide to form iron cyanide. The pH of the wastewater can be raised stepwise to a level in the range of 7 to 11, for example to a level in the range of about 9-11, even 9-10. The water-insoluble CN-containing sludge that settles consists essentially of iron cyanide. Conventional solid-liquid separation means in step (3) include those specified above, such as filters,
It can be a centrifuge, a hydrocyclone, a clarifier, a settling tank or a combination thereof. For example, the water-insoluble substances in step (3) can be separated from the water in a settling tank or clarifier, and the resulting water stream can then be passed through a Punto filter to serve the clarified water stream. Depending on the packaging, a flocculant/coagulant, for example a cationic plastite, can also be mixed into the gray water in step (1). The conversion of formates and other organic carbonaceous substances in hot water to carbon dioxide and biological residues is carried out in a bioreactor containing biologically active solids according to conventional procedures. The biological residue separated in step (7) can be dried and used as fuel.

The remediation water stream from the bioreactor has approximately the following analytical values (in ppm): less than 10 nickel, vanadium, iron, sulfide, SCN, free CN, and sulfide, respectively; 3
．． Total CN below O; biochemical oxygen demand below 10 (
BOD ) (after filtration); ammonia below 20; 40
BOD (before filtration) and total suspended solids below; and 50
Formate below.

EXPERIMENTAL EXAMPLES The following examples illustrate the operation of the method of the invention.
It should not be construed as limiting the scope of the invention.

Wastewater, e.g., effluent from a partial oxidation process for synthesis gas production, as described in Applicant's U.S. Pat. No. 4,141,696, incorporated by reference a-aF, When analyzing nickel, it is 1.32
It contained mg/l of soluble nickel. Temperature 32℃
Formaldehyde or sodium sulfide was added to separate samples of wastewater, pH 9.5, at the concentrations shown in the following table. 10 mg/l dimethyl glyochim was also added to each sample of wastewater. A precipitate consisting of a nickel-dimethyl briochytum complex formed. Samples were filtered and analyzed for water-soluble nickel. The final soluble nickel content in each sample of improved water is shown in Table I below. As you can see from this result,
The soluble nickel content in the original sample of wastewater was reduced by approximately 66 to 86 nickels, depending on the type and amount of added chemicals. During pregnancy, the nickel content decreased to less than about 5 mL.

Table 1 Formaldehyde in improved wastewater before chemical addition Sodium polysulfide Nickel content 20
0.3450
0.21100
-0.19-
10 0.53-
20 0.42-10
0 0.26 Procedural Amendment (T-1, Case Indication 1985 Patent Application No. 24-217 'r No. 2, Order E
1st name Mochi Nakatsu Niso Busy (shiincludes i”t@pτep7:s23, Relationship with the person making the amendment Patent applicant name (name)
Te"i,'Tco゛T Veloso 2ㅅ←・Koho 0 Reni Nikoni 5, Date of □ Date of 1937, Tamatsuki 2g, Japan 6th, Specification subject to amendment

Claims (1)

Claims: 1. A method for reducing the content of soluble or insoluble nickel-containing impurities and water-insoluble substances in a wastewater stream, comprising: a)
(b) mixing with a water-soluble substance selected from formaldehyde, ionizable polysulfides, and hydrogen peroxide; and (2) adding a base to the resulting mixture to bring the pH to a value of 7 to 11. A method for reducing the nickel content in wastewater, characterized in that it consists in precipitating a water-insoluble nickel-dimethyl glyoxime complex (if it has not already reached the desired value). 2. The method according to claim 1, characterized in that in step (1), a flocculant/coagulant is added to the wastewater. 3. In step (1), the wastewater is mixed with 1.2 to 10 moles of ferrous compound per mole of total cyanide in the wastewater to produce water-insoluble inorganic CN-containing sludge, iron hydroxide and iron sulfide, and A method according to claim 1, characterized in that the nickel-dimethyl glyoxime complex is precipitated. 4. Raise the pH of the improved water stream after separation of precipitated solids to a minimum of 11 if the pH is below 11, strip ammonia from the waste stream, and reduce the pH of the water stream after NH_3 stripping to a minimum of 6 to 8. 4. Process according to claim 3, characterized in that the formate salts are converted into CO_2 after being adjusted to a value of .